<?php

/*
 * Created on June 14, 2007
 *
 * API for MediaWiki 1.8+
 *
 * Copyright (C) 2006 Yuri Astrakhan <Firstname><Lastname>@gmail.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 * http://www.gnu.org/copyleft/gpl.html
 */

if ( !defined( 'MEDIAWIKI' ) ) {
	// Eclipse helper - will be ignored in production
	require_once ( "ApiQueryBase.php" );
}

/**
 * A query module to enumerate pages that belong to a category.
 *
 * @ingroup API
 */
class ApiQueryCategoryMembers extends ApiQueryGeneratorBase {

	public function __construct( $query, $moduleName ) {
		parent :: __construct( $query, $moduleName, 'cm' );
	}

	public function execute() {
		$this->run();
	}

	public function getCacheMode( $params ) {
		return 'public';
	}

	public function executeGenerator( $resultPageSet ) {
		$this->run( $resultPageSet );
	}

	private function run( $resultPageSet = null ) {

		$params = $this->extractRequestParams();

		if ( !isset( $params['title'] ) || is_null( $params['title'] ) )
			$this->dieUsage( "The cmtitle parameter is required", 'notitle' );
		$categoryTitle = Title::newFromText( $params['title'] );

		if ( is_null( $categoryTitle ) || $categoryTitle->getNamespace() != NS_CATEGORY )
			$this->dieUsage( "The category name you entered is not valid", 'invalidcategory' );

		$prop = array_flip( $params['prop'] );
		$fld_ids = isset( $prop['ids'] );
		$fld_title = isset( $prop['title'] );
		$fld_sortkey = isset( $prop['sortkey'] );
		$fld_timestamp = isset( $prop['timestamp'] );

		if ( is_null( $resultPageSet ) ) {
			$this->addFields( array( 'cl_from', 'cl_sortkey', 'page_namespace', 'page_title' ) );
			$this->addFieldsIf( 'page_id', $fld_ids );
		} else {
			$this->addFields( $resultPageSet->getPageTableFields() ); // will include page_ id, ns, title
			$this->addFields( array( 'cl_from', 'cl_sortkey' ) );
		}

		$this->addFieldsIf( 'cl_timestamp', $fld_timestamp || $params['sort'] == 'timestamp' );
		$this->addTables( array( 'page', 'categorylinks' ) );	// must be in this order for 'USE INDEX'
									// Not needed after bug 10280 is applied to servers
		if ( $params['sort'] == 'timestamp' )
			$this->addOption( 'USE INDEX', 'cl_timestamp' );
		else
			$this->addOption( 'USE INDEX', 'cl_sortkey' );

		$this->addWhere( 'cl_from=page_id' );
		$this->setContinuation( $params['continue'], $params['dir'] );
		$this->addWhereFld( 'cl_to', $categoryTitle->getDBkey() );
		// Scanning large datasets for rare categories sucks, and I already told 
		// how to have efficient subcategory access :-) ~~~~ (oh well, domas)
		global $wgMiserMode;
		$miser_ns = array();
		if ( $wgMiserMode ) {
			$miser_ns = $params['namespace'];
		} else {
			$this->addWhereFld( 'page_namespace', $params['namespace'] );
		}
		if ( $params['sort'] == 'timestamp' )
			$this->addWhereRange( 'cl_timestamp', ( $params['dir'] == 'asc' ? 'newer' : 'older' ), $params['start'], $params['end'] );
		else
		{
			$this->addWhereRange( 'cl_sortkey', ( $params['dir'] == 'asc' ? 'newer' : 'older' ), $params['startsortkey'], $params['endsortkey'] );
			$this->addWhereRange( 'cl_from', ( $params['dir'] == 'asc' ? 'newer' : 'older' ), null, null );
		}

		$limit = $params['limit'];
		$this->addOption( 'LIMIT', $limit + 1 );

		$db = $this->getDB();

		$data = array ();
		$count = 0;
		$lastSortKey = null;
		$res = $this->select( __METHOD__ );
		while ( $row = $db->fetchObject( $res ) ) {
			if ( ++ $count > $limit ) {
				// We've reached the one extra which shows that there are additional pages to be had. Stop here...
				// TODO: Security issue - if the user has no right to view next title, it will still be shown
				if ( $params['sort'] == 'timestamp' )
					$this->setContinueEnumParameter( 'start', wfTimestamp( TS_ISO_8601, $row->cl_timestamp ) );
				else
					$this->setContinueEnumParameter( 'continue', $this->getContinueStr( $row, $lastSortKey ) );
				break;
			}

			// Since domas won't tell anyone what he told long ago, apply 
			// cmnamespace here. This means the query may return 0 actual 
			// results, but on the other hand it could save returning 5000 
			// useless results to the client. ~~~~
			if ( count( $miser_ns ) && !in_array( $row->page_namespace, $miser_ns ) )
				continue;

			if ( is_null( $resultPageSet ) ) {
				$vals = array();
				if ( $fld_ids )
					$vals['pageid'] = intval( $row->page_id );
				if ( $fld_title ) {
					$title = Title :: makeTitle( $row->page_namespace, $row->page_title );
					ApiQueryBase::addTitleInfo( $vals, $title );
				}
				if ( $fld_sortkey )
					$vals['sortkey'] = $row->cl_sortkey;
				if ( $fld_timestamp )
					$vals['timestamp'] = wfTimestamp( TS_ISO_8601, $row->cl_timestamp );
				$fit = $this->getResult()->addValue( array( 'query', $this->getModuleName() ),
						null, $vals );
				if ( !$fit )
				{
					if ( $params['sort'] == 'timestamp' )
						$this->setContinueEnumParameter( 'start', wfTimestamp( TS_ISO_8601, $row->cl_timestamp ) );
					else
						$this->setContinueEnumParameter( 'continue', $this->getContinueStr( $row, $lastSortKey ) );
					break;
				}
			} else {
				$resultPageSet->processDbRow( $row );
			}
			$lastSortKey = $row->cl_sortkey;	// detect duplicate sortkeys
		}
		$db->freeResult( $res );

		if ( is_null( $resultPageSet ) ) {
			$this->getResult()->setIndexedTagName_internal(
					 array( 'query', $this->getModuleName() ), 'cm' );
		}
	}

	private function getContinueStr( $row, $lastSortKey ) {
		$ret = $row->cl_sortkey . '|';
		if ( $row->cl_sortkey == $lastSortKey )	// duplicate sort key, add cl_from
			$ret .= $row->cl_from;
		return $ret;
	}

	/**
	 * Add DB WHERE clause to continue previous query based on 'continue' parameter
	 */
	private function setContinuation( $continue, $dir ) {
		if ( is_null( $continue ) )
			return;	// This is not a continuation request

		$pos = strrpos( $continue, '|' );
		$sortkey = substr( $continue, 0, $pos );
		$fromstr = substr( $continue, $pos + 1 );
		$from = intval( $fromstr );

		if ( $from == 0 && strlen( $fromstr ) > 0 )
			$this->dieUsage( "Invalid continue param. You should pass the original value returned by the previous query", "badcontinue" );

		$encSortKey = $this->getDB()->addQuotes( $sortkey );
		$encFrom = $this->getDB()->addQuotes( $from );
		
		$op = ( $dir == 'desc' ? '<' : '>' );

		if ( $from != 0 ) {
			// Duplicate sort key continue
			$this->addWhere( "cl_sortkey$op$encSortKey OR (cl_sortkey=$encSortKey AND cl_from$op=$encFrom)" );
		} else {
			$this->addWhere( "cl_sortkey$op=$encSortKey" );
		}
	}

	public function getAllowedParams() {
		return array (
			'title' => null,
			'prop' => array (
				ApiBase :: PARAM_DFLT => 'ids|title',
				ApiBase :: PARAM_ISMULTI => true,
				ApiBase :: PARAM_TYPE => array (
					'ids',
					'title',
					'sortkey',
					'timestamp',
				)
			),
			'namespace' => array (
				ApiBase :: PARAM_ISMULTI => true,
				ApiBase :: PARAM_TYPE => 'namespace',
			),
			'continue' => null,
			'limit' => array (
				ApiBase :: PARAM_TYPE => 'limit',
				ApiBase :: PARAM_DFLT => 10,
				ApiBase :: PARAM_MIN => 1,
				ApiBase :: PARAM_MAX => ApiBase :: LIMIT_BIG1,
				ApiBase :: PARAM_MAX2 => ApiBase :: LIMIT_BIG2
			),
			'sort' => array(
				ApiBase :: PARAM_DFLT => 'sortkey',
				ApiBase :: PARAM_TYPE => array(
					'sortkey',
					'timestamp'
				)
			),
			'dir' => array(
				ApiBase :: PARAM_DFLT => 'asc',
				ApiBase :: PARAM_TYPE => array(
					'asc',
					'desc'
				)
			),
			'start' => array(
				ApiBase :: PARAM_TYPE => 'timestamp'
			),
			'end' => array(
				ApiBase :: PARAM_TYPE => 'timestamp'
			),
			'startsortkey' => null,
			'endsortkey' => null,
		);
	}

	public function getParamDescription() {
		global $wgMiserMode;
		$desc = array (
			'title' => 'Which category to enumerate (required). Must include Category: prefix',
			'prop' => 'What pieces of information to include',
			'namespace' => 'Only include pages in these namespaces',
			'sort' => 'Property to sort by',
			'dir' => 'In which direction to sort',
			'start' => 'Timestamp to start listing from. Can only be used with cmsort=timestamp',
			'end' => 'Timestamp to end listing at. Can only be used with cmsort=timestamp',
			'startsortkey' => 'Sortkey to start listing from. Can only be used with cmsort=sortkey',
			'endsortkey' => 'Sortkey to end listing at. Can only be used with cmsort=sortkey',
			'continue' => 'For large categories, give the value retured from previous query',
			'limit' => 'The maximum number of pages to return.',
		);
		if ( $wgMiserMode ) {
			$desc['namespace'] = array(
				$desc['namespace'],
				'NOTE: Due to $wgMiserMode, using this may result in fewer than "limit" results',
				'returned before continuing; in extreme cases, zero results may be returned.',
			);
		}
		return $desc;
	}

	public function getDescription() {
		return 'List all pages in a given category';
	}
	
	public function getPossibleErrors() {
		return array_merge( parent::getPossibleErrors(), array(
			array( 'code' => 'notitle', 'info' => 'The cmtitle parameter is required' ),
			array( 'code' => 'invalidcategory', 'info' => 'The category name you entered is not valid' ),
			array( 'code' => 'badcontinue', 'info' => 'Invalid continue param. You should pass the original value returned by the previous query' ),
		) );
	}

	protected function getExamples() {
		return array (
				"Get first 10 pages in [[Category:Physics]]:",
				"  api.php?action=query&list=categorymembers&cmtitle=Category:Physics",
				"Get page info about first 10 pages in [[Category:Physics]]:",
				"  api.php?action=query&generator=categorymembers&gcmtitle=Category:Physics&prop=info",
			);
	}

	public function getVersion() {
		return __CLASS__ . ': $Id: ApiQueryCategoryMembers.php 69932 2010-07-26 08:03:21Z tstarling $';
	}
}
